Stock muffler

[Spec83]

It's nothing to do with engine over heating, that would be the radiator not doing it's job.

The intercooler cools the air going into the engine. Cooler air is more dense which means more air gets in and that means more air coming out.

To expand on this point.. The cooler the intake air, the more fuel and timing advance can be added to the engine before the air/fuel mixture becomes that hot (due to block temperatures) that it ignites in the cylinder bore before the ignition stroke of the engine.. This is very bad as it sends the whole engine out of balance and results in a condition commanly known as 'knocking'...

The basic principal of a combustion engine is - (fuel+air) * spark = Killo'wasps'

I belive the 1.8T has built in knock sensors which retard the timing to prevent this from happening..

[Buller_Scott]

To expand on this point.. The cooler the intake air, the more fuel and timing advance can be added to the engine before the air/fuel mixture becomes that hot (due to block temperatures) that it ignites in the cylinder bore before the ignition stroke of the engine.. This is very bad as it sends the whole engine out of balance and results in a condition commanly known as 'knocking'...

The basic principal of a combustion engine is - (fuel+air) * spark = Killo'wasps'

I belive the 1.8T has built in knock sensors which retard the timing to prevent this from happening..

thanks for the detail- i just wanted to ask, so does that mean if i have other mods done but HAVE NOT done the fmic, that creates knocking due to excessive heat/ pre-mature fuel ignition?

if so, when would this happen? is 'knocking' something that typically is really only seen on dyno days/ track days, or do you know of people who have had daily driver setups without intercooler but with other mods, who have had this problem? cheers

[Bubu]

thanks for the detail- i just wanted to ask, so does that mean if i have other mods done but HAVE NOT done the fmic, that creates knocking due to excessive heat/ pre-mature fuel ignition?

if so, when would this happen? is 'knocking' something that typically is really only seen on dyno days/ track days, or do you know of people who have had daily driver setups without intercooler but with other mods, who have had this problem? cheers

We are so way off the topic of origial post. You should have just started a new thread. Anyway...

In short no it does not create knocking. As Spec83 said the Polo is ftted with a knock sensor which enables the engine to adjust fuel and timing as necessary.

Kocking can occour on just about any car and it can damage your engine internals very quickly. Knocking most commonly occours when the engine is under load.

I have known people to have problems with knocking on their turbocharged cars. However this is usually due to bad tuning or too much advance timing (which relates to tuning).

All this is not really a problem for you if you have a current model Polo because the factory ECU is very smart and it wont allow the engine to 'knock'. It will probably go into a limp mode at worst case scenario.

[Timbo]

There's an important detail here: IIRC, Buller_Scott's car is a diesel, so some different principles apply

[VW GTI]

how long (after roughly how many minutes) did this heat soak set in and cause Rhys' car to drop power (never been to a dyno day, dont know format)?

oh and thanks for the replies- they're really informative. if i can avoid an intercooler (cost), i will, but i also DO like to rip it up the bends on the way to buller, and when its a clear road that's about 16km's and 10-12 mins of thrashing its orse off....

Well, at the dyno day it was only a matter of minutes of running the car, but the only 'cooling' there is is a big fan at the front of the car (I think the fan was even turned off briefly to speed the process up?).

When you're driving air is rushing past you all the time and would probably be cooler air (especially up in the mountains). So the timeframe changes entirely.

[Sharkie]

You have to remember as well that a FMIC sits right in front and not on the side with restricted airflow. On the road the difference to a Dyno test is even greater as you get a lot of cold fresh air shoved straight at it and the faster you go the more air it gets.

More and cooler air = more power due to lower intake temps ... and longer life out of the whole engine.

To me a FMIC is a no brainer .....

[RhysQ]

Scott,

my car was used for both the 'completely stock' and 'just chipped' runs, which consisted of 3 runs for each setting. the stock run was done first with a heatsoak test done just before the last run (which is when they get the car running up to about 4,000rpm for a few seconds and then drop back off....do this a few times and voila, heatsoak!).

the chipped runs were done next so the car really didn't get a good chance to cool down but 123.8kW at the wheels given the circumstances i was very happy with. same thing this time, first two runs being 123.8 and ~121-2kW, then after heatsoaking i think there were one or two more runs done which saw my car drop way down to ~100kW atw....

sharkie had just the APR ECU and FMIC and each of his runs were consistent at ~129kW...no heatsoak effect as the intake temp stayed cool throughout each run thanks to the FMIC.

as for time heatsoak takes to set in, i'd say give the car about 4-5 decent punches from a standstill and your power will be significantly less. driving conservatively maybe about 5 mins, about the time it takes for your car to really heat up.

Cheers,
Rhys

[Sharkie]

Also, I have spoken to Guy a while ago and the TDI Polo also has a very restrictive SMIC. An upgrade to a FMIC will realise more power as well as other benefits.

[Adam]

Lol. was reading the 2nd page of this post.. and after reading most of it.. I actually thought the post was about intercoolers...and had to think twice and look at the title again..oh mufflers..

[Sharkie]

Yeah, isnt it amazing how a thread can be diverted ....